Evaluation of the variation in sensory test results using Semmes-Weinstein monofilaments

Abstract

The purpose of this study is to examine the variability in sensory test of tactile results using Semmes-Weinstein monofilament (SWM). At present, several methods for measuring the tactile sensitivity are clinically used in diabetic peripheral neuropathy screening. One of these methods is a touch test that uses a device with nylon SWMs, i.e., SWMs embedded in a plastic handle. A small pushing force is applied at the handle to bow the filaments. Because of its ease and simplicity, the SWM test is conducted at the patient's bedside in a hospital. However, previous studies have reported some problems with this test. Studies have shown variations in the measured data, and it is uncertain whether these variations are caused by mechanical properties of the nylon fiber or by the motion of the operator's hands. We carried out two experiments to examine the effect of (1) the variability caused by the human operator conducting the SWM test on the test results and (2) the number of compressions of the SWM on the test results. In experiment 1, we measured the velocity of the operator's hand motion and the buckling force of the SWMs. The results showed variability in the hand motion of the operator conducting the SWM tests. In experiment 2, we measured the buckling force of the SWMs under a controlled velocity. We compared the buckling force of the SWMs through a number of trials. These results showed that the buckling force gradually decreases as the number of test cycles increase. In conclusion, we find that the accuracy of the SWM tests is a factor of the number of test cycles. Additionally, manual training for standardizing skills of medical staff members needs to be developed. Furthermore, the characteristics of the SWMs deteriorated over time. In future work, we aimto find a solution to minimize the variability in the SWM test results and develop a new testing system that uses tactile sensibility for diabetic peripheral neuropathy screening.

Buckling Force Variability of Semmes–Weinstein Monofilaments in Successive Use Determined by Manual and Automated Operation

“…In the manual operation experiment (experiment 1), we measured the buckling force and compared the force values among 10 trials. The human hand motion with a monofilament differed among individuals, as in the previous study [21]. On average, although the buckling force monotonically decreased in 10 successive trials, the velocity of the hand motion and the contact angle did not show monotonic changes.…”

“…However, several studies [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ] have previously reported concerns about the mechanical properties of monofilaments (for a review, see [ 16 ]). For example, Booth et al [ 17 ] reported that the maximum recovery of the buckling force in any monofilament is achieved within 24 h and discussed the variability of force on a simulated skin surface in the results of the SWMT.…”

“…Further, Lavery et al [ 20 ] reported that the buckling force of a new monofilament is only stable for seven to nine days, or for the evaluation of 70 to 90 patients. Chikai et al [ 21 ] compared a new, multi-use monofilament (with the same buckling force, i.e., 5.07/10 gf) with an old one, and showed that the buckling force of the monofilament decreased through numerous test trials. In contrast, Bell-Krotoski et al [ 22 ] showed that the SWMT provides a repeatable instrument stimulus with a small standard deviation in contrast to other handheld test instruments in a variety of clinics.…”

Outpatient vs Home Management Protocol Results for Plantar Fasciitis

“…32 A monofilament test was performed to evaluate foot sense in specific areas. 11 All patients were examined at the beginning and post management at the eighth week and sixth month. VAS and FFI scores were completed by phone at the sixth month.…”

A notação logarítmica como opção de registro objetivo da estesiometria: um estudo piloto

“…Os dispositivos analógicos, mesmo os validados, usualmente manifestam poder de reprodutividade com maiores desvios que seus paralelos digitais 6,7 , como é o caso do estesiômetro do tipo monofilamentos de Semmes-Weinstein 8 . Em parte, o comprometimento da acurácia dos dados durante a coleta é causado por variabilidade entre avaliadores diferentes ou pela dispersão entre as áreas das secções transversais de um monofilamento para outro, com valores nominais notadamente diferentes 9 . Isso pode ser um problema quando o monofilamento em teste tem secção transversal maior que o necessário para estimular o campo receptivo da pele ou o atual estado de sensibilidade.…”